Unblock with 'mysqladmin flush-hosts' Mysql 5 and greater

Many times we get this error due to

wrong authentication (username or password incorrect)
too many connections from same machine.

easiest way for this, is ..

clear with flush-hosts command. See http://dev.mysql.com/doc/refman/5.1/en/flush.html

STEPS for Linux

open terminal window type

mysqladmin -uroot -ppassword flush-hosts;

[Remember -uroot is your root name with a "-u" before it, and same for password "-p" before password]

You are done.


Another tip 1
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Restarting MySQLd solves the problem. FLUSH HOSTS also wipes the internal DNS cache, so be careful with its use - a flood of reverse DNS lookups can severely limit your server’s speed!

open the terminal and type (for Linux)

/etc/init.d/mysql restart


Another tip 2 allow many connections
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To increase the maximum connections that mysql allows, you must edit the file /etc/my.cnf. Log into the server as root and type

nano /etc/MYSQL/my.cnf

it will open the config file (depending upon your cnf file location change the path) and uncomment (remove #) to the following line with the allowed no of connections e.g.

max_connections=10000 

Now press CTRL+X and Yes (Y) to exit from terminal window. Now Type

/etc/init.d/mysql restart 

you will see on the terminal screen

Stopping MySQL database server mysqld: [ OK ]
Starting MySQL database server mysqld: [ OK ]

You are done.

CHECK THE SETTING IS PROPER OR NOT...

If you'd like to check to see if this setting was successfully applied, you may check using one of the following methods:

1. login to mysql

   mysql -uadmin -ppassword

   or through mysql administrator tool (Go to tools->MySQL text Console), you will be at the "mysql>" prompt.
   
   
2. Then give the command

   show variables like 'max_connections'; 

   make sure you put the semi-colon on the end. To exit mysql, use the "quit" command